Additive System for Lubricating Fluids

ABSTRACT

The invention concerns an additive package for a lubricating fluid or grease containing an effective amount of a phosphorus-containing antiwear additive, the improvement comprising the absence of primary, secondary, tertiary, cyclic low molecular weight aliphatic amines with a carbon number of C30 or less.

FIELD OF THE INVENTION

The invention relates to an additive system having essentially nohydrocarbyl amine rust inhibitor of C30 or less, suitable for use inlubricating fluids, and a fully formulated lubricating fluid containingsaid additive system.

BACKGROUND OF THE INVENTION

Oxidative stability, seal compatibility, protection from wear, andoverall durability are highly sought after features of gears oils forboth automotive and industrial applications. Original equipmentmanufacturers (OEMs) as well as the consuming public are constantlydemanding improvements such as extended drain intervals from suppliersof gear oils.

Enhanced oxidative stability is highly desired in driveline fluids(e.g., automotive transmissions and differentials) as well as in gearboxes used for various industrial applications. When oxidation isproblematic, sludge and carbon/varnish deposits appear on the gearsurfaces, which may adversely impact the functioning of the gears.Lubricants are expected to be able to pass lengthy oxidation tests, e.g.the extended L-60-1 test (comprising a 200 hr test for axle oils and 300hr test for transmission oils). The lubricant should be able to provideadequate cleanliness as well as viscosity control to pass these tests.

In order to prepare lubricants which are oxidatively stable, it hasbecome common practice to add antioxidants to the lubricating oil,either phenolic or arylamine types. Alternatively, formulators canchoose to use certain base stocks and/or additive combinations which areless prone to oxidation.

Gear oils that are expected to survive for long drain intervals shouldalso be able to leave seals undamaged so that no leakage occurs duringthe lifetime of the gear box. Axle and transmission seal materials inthe U.S. and Europe include fluoroelastomer, nitrile and polyacrylate.Static and dynamic seal testing in the U.S. and Europe are part ofindustry and OEM performance specifications for both industrial andautomotive gear oil.

One of the most important features of a gear oil is its ability toprevent gear distress, which if severe enough, can ultimately lead tocatastrophic failure of the gears. Gear distress or wear can be in theform of pitting, spalling, ridging, rippling, etc. for automotive gears,especially those in the differential because of the loads. To controlwear, it is common to add anti-wear additives to reduce or preventdamage. These additives preferably should be able to function attemperatures from sub-zero to temperatures around 160° C., which couldbe reached if the vehicle is subjected to severe operating conditions.In addition, to perform most effectively, anti-wear additives preferablyshould be able to function in the presence of other aggressive additivesthat perform key functions, e.g. extreme pressure additives, and theypreferably should be able to continue to function for long operatingperiods.

There are industry tests for examining the effectiveness of antiwearadditive systems. In the automotive industry, the L-37 is most widelyrecognized. This rig test simulates low speed, high torque operation. Alow temperature modification of this test is also part of the API GL-5and SAE J2360 specification for 75W graded gear lubricants. The lowtemperature version of this test is known as the Canadian version. Therealso exists a high temperature version of the L-37 test, which isincluded in several OEM specifications. In the L-37 test, and itsvariants, the gears are disassembled at the end of the test and the geardistress is rated.

Commonly used anti-wear additives are phosphorous containing compounds.They usually include amine-neutralized salts of phosphorus acids,phosphinyl acids, phosphonyl acids, thiophosphorus acids, thiophosphinylacids, thiophosphonyl acids, and the partial esters of these. The aminesuseful in preparing the amine salts are primary or secondary hydrocarbylmonoamines or polyamines containing about 4-30 carbon atoms. They mayalso be tertiary or cyclic amines. The most common amines are primary,fatty amines containing 10-20 carbon atoms, like octadecyl amine ortertiary alkyl amines like C12-C14 tertiary alkyl primary amine,commercially available as “Primene 81-R.” It is commonly believed thatthe amine neutralization is a necessary feature of the differentphosphorus-containing compounds, because of its ability to impartcritically required steel corrosion protection and thermal stability.

In order to reach the extended drain intervals that OEMs are now seekingfor their gear boxes and differentials, durability is important for gearoils, both automotive and industrial. The durability of a fluid willdepend on the base oils that are being used, e.g. synthetic base oilswill be far more durable than API Group I and II fluids because of thesuperior oxidative and thermal stability. However, base oil selection isonly part of the picture for formulating gear oils with improveddurability. The additive system must also be carefully chosen so as toprovide oxidation stability, seal compatibility and antiwearperformance, all of which contribute to an oil's durability.

Industrial and automotive gear lubes perform in much the same way,though loads on the industrial gears tend to be spread out over largersurface areas and therefore are not as great as those seen in the rearaxle of an automotive vehicle. Nevertheless, similar features would beconsidered desirable in both types of gear oils. Durability, forexample, is important as this would equate to longer drain intervals andreduced down time and reduced maintenance costs. Durability in the formof improved oxidative stability, reduced wear and better sealcompatibility are highly desired for all types of gear oils.

Because there are numerous additives added to such compositions for manydiverse reasons and with each additive interacting with all the otheradditives in some manner, it is extremely difficult to find newformulations showing an improvement in at least one property whilehaving little or no detrimental effects on other properties.Nevertheless, the prior art is filled with many attempts to prepare gearadditive concentrates and gear lubricant compositions with improvementsin the areas of extreme pressure/antiwear, thermal stability, oxidativestability and the like.

U.S. Pat. No. 6,844,300 and EP 1 233 051 A1 teach that a gear oilcomprising a base oil, a thermally stable P-containing antiwear additiveand a metal free sulfur EP agent, wherein the S is present at least at alevel of 10,000 ppms, and the P is present from 100-350 ppms will meetGL-5 requirements. The thermally stable antiwear additive is defined asoil soluble amine salts of phosphoric acid esters as well as reactionproducts of dicyclopentadiene and thiophosphoric acid. The salts may beformed beforehand or in situ.

U.S. Pat. No. 6,046,144 describes synergistic antioxidant compositionscomprising amine salts of alkyl phosphates, and ethylenediamine,ammonium or metal salts of alkylarylsulfonates.

U.S. Pat. No. 5,942,470 teaches the use of combining at least one oilsoluble sulfur-containing extreme pressure or antiwear agent with atleast one oil soluble amine salt of a partial ester of an acid ofphosphorus and with at least one oil soluble succinimide dispersant of aformula defined in the patent. A lengthy list of many suitable aminesalts of the partially esterified phosphorus is included in the patent.Primary amines are preferred.

U.S. Pat. No. 5,763,372 discusses “clean gear” boron-free gear additivesystems, which employ an ashless boron-free dispersant, a sulfur source,and a phosphorus source, wherein at least one is chosen from a group ofoil-soluble amine salts of acid phosphates.

U.S. Pat. No. 5,756,429 describes a composition suitable for high speedgears having a peripheral speed of at least 10 msec containing a baseoil having a % Ca of 5 or less and a S, P, N ratio of 100N/(S+P) between4 and 10 by weight. Use of acid phosphates and their amine salts arepreferred. The composition is said to be able to inhibit sludge andpermit the prolongation of the life of an oil seal.

U.S. Pat. No. 5,691,283 describes a transmission and axle ordifferential gearing which comprises a base oil and a Mannichdispersant, a sulfur-containing EP agent, a P- and N-containing antiwearadditive, and an overbased alkali or alkaline earth carboxylate,sulphonate, or sulfurized phenate having a TBN (Total Base Number) of atleast 145.

U.S. Pat. No. 5,573,696 and U.S. Pat. No. 5,500,140 discuss thepreparation of amine-neutralized acid phosphates, which are prepared byreacting P₂O₅ with an alcohol prepared from the reaction of an epoxidewith dihydrocarbyl phosphorothioic acid.

U.S. Pat. No. 5,547,596 describes a lubricant composition for thelimited slip differential (LSD) of a car which is obtained by adding aphosphate amine salt, such as an amine salt of an oleyl acid phosphateand a borated ashless dispersant, such that the ratio of N/P is 0.5-1.0;the ratio of N/B is 4-10; the phosphorus content is in the range of0.15-0.4% by weight; and the boron content is in the range of 0.01 to0.04% by weight. This lubricant composition inhibits the generation ofchattering during the operation of a LSD device and has excellentoxidative stability.

U.S. Pat. No. 5,358,650, U.S. Pat. No. 5,571,445, and WO 94/22990describe a synthetic fluid which includes a variety of synthetic baseoils plus specified amounts of the following: a sulfur-containingextreme pressure-antiwear agent, a P-containing antiwear agent, acorrosion inhibitor, an amine and/or carboxylic acid rust inhibitor, afoam inhibitor, and an ashless dispersant.

U.S. Pat. No. 5,354,484 describes how improved high temperaturestability can be achieved with the presence of at least one solubletertiary aliphatic primary amine salt, wherein the primary aminecontains 4-30 carbon atoms, at least one of which is a substitutedphosphoric acid, in combination with a borated succinimide dispersant.

U.S. Pat. No. 5,328,619 describes an additive concentrate comprising atleast one oil soluble organic acid, e.g. one or more hydrocarbylphosphoric acids, one or more carboxylic acids or a combination of thetwo, and a hydrocarbyl amine which is added such that the pH of thefinished concentrate is in the 6.0-7.0 range. A borated dispersant isintroduced into the concentrate being formed when the concentrate is atleast 6.0. The resulting compositions are said to inhibit haze in theresulting concentrates, and the pH control can provide gear compositionshaving enhanced extreme pressure performance in the L-42 test, andimproved rust in the L-33 test.

U.S. Pat. No. 4,575,431 discusses the combination of dihydrocarbylhydrogen thiophosphates and hydrocarbyl dihydrogen phosphates anddihydrocarbyl hydrogen phosphates, with the phosphates being at least50% neutralized with a hydrocarbyl amine that is C10-C30.

U.S. Pat. No. 4,431,552 discusses a lubricating composition havingdispersed therein a hydrated alkali metal borate extreme pressure agentand an effective amount of a mixture of a phosphate, amonothiophosphate, and a dithiophosphate. All of the phosphates arepreferably used as their hydrocarbyl amine salts.

U.S. Pat. No. 4,118,328 discusses the preparation and use of phosphatesalts comprised of heating a triaryl phosphate and a primary orsecondary aliphatic amine in a 1-20 molar ratio, respectively, with atrace amount of boric acid for catalyst.

U.S. Pat. No. 3,728,260 describes the preparation of a neutralhydrocarbyl phosphate in combination with an alkyl amine hydrocarbylphosphate salt for improved load carrying.

EP 531 585 describes the use of an additive composition which includes aborated Mannich dispersant, a sulfur containing anti-wear or EP agent, ametal free phosphorus-containing antiwear-EP agent, and an oil-solubleamine salt of a carboxylic acid. Free amine may or may not be present,and may or may not be complexed to the phosphorus antiwear agent.

EP 519 760 B1 teaches that an oil soluble amine is used to adjust the pHof an additive concentrate to 6-7 then dispersant is added after thisadjustment is made.

EP 391 653 B1 and EP 450 208 B1 both discuss having high concentrationsof amines along with suitable quantities of weak acids, e.g. carboxylicacids, in the presence of sulfurized isobutylene and P-containingantiwear additives to provide gear oils with improved gear performancebased on the results of a Planetary Spur Gear Test.

UK 2,108,147 examines the use of oil soluble overbased sodium salts ofphosphate esters in lubricant compositions.

WO 03/1004620 A2 discusses a lubricating composition with improvedefficiency for an emissions control system, wherein the compositionscontain a metal-containing detergent, a metal salt of one or morephosphorus acids or the corresponding esters, and an acylatednitrogen-containing compound having at least 10 carbon atoms. Theresulting TBN composition has a phosphorus concentration of up to about0.12%.

U.S. Pat. No. 4,900,460 covers sulfurized olefins reacted withphosphates and phosphites. The reaction product is useful as an extremepressure and wear additive for lube compositions.

U.S. Pat. No. 3,513,093 describes a composition containing a major partof a lubricating oil and minor portion of a substituted polyamine, whichis prepared by reacting a polyamine with a succinic acid producinghydrocarbon having at least 50 carbons with at least 0.001 moles of aphosphorus acid producing compound selected from the class of phosphoricacids, phosphorus acids, phosphonyl acids, phosphinyl acids, etc. Thesespecies were found to give improved oxidation performance in a varietyof bench and engine tests.

U.S. Pat. No. 2,224,695 teaches the preparation of a corrosion inhibitorfor metals which comprises an ester of an acid of phosphorus having atleast one of the hydrogen atoms of the acid replaced by an ester groupand at least one of the hydrogen atoms replaced by an inorganic radical,upon exposing it to a metal surface. Under favorable conditions, itreacts chemically with metal surfaces to form a protective coating andinhibit corrosive wear.

EP 531 000 B1 discusses an additive composition containing a.) areaction product of a phosphorus or thiophosphorus acid with an ashlessdispersant and a boron compound and b.) a sulfur containing antiwear-EPagent. The gear oil prepared with these components is said to have theseperformance improvements: 1.) inhibition of scoring/scuffing, 2.)improved wear in the form of ridging, rippling, pitting and spalling,3.) improved oxidation in the form of reduced sludge and varnishdeposits, especially at higher temperatures.

The present inventors have surprisingly discovered an additive package,suitable for preparing a lubricant or grease composition, that does notmake use of primary, secondary, tertiary, or cyclic aliphatic lowmolecular weight (<C30) amines and therefore, it does not contain thecorresponding acid phosphate amine salts, and yet, it provides forlubricants exhibiting, in preferred embodiments, improved performance inat least one of the areas of oxidative stability, seal compatibility,and anti-wear protection, while causing no significant deficits in otherimportant areas of performance.

SUMMARY OF THE INVENTION

The invention is directed to an additive package for lubricating fluidsor greases, the improvement characterized by the absence of primary,secondary, tertiary and cyclic hydrocarbyl amines with a carbon numberof C30 or less and the absence of the corresponding acid phosphate aminesalts.

In an embodiment, the additive system is further characterized bypossessing a total base number (TBN) of less than 22.

In an embodiment, the invention is further characterized as comprisingan effective amount of an acid phosphate antiwear additive. In preferredembodiments, the phosphate antiwear additive will be at least one mono-and/or dialkyl acid phosphate effective for antiwear protection.

Preferred mono- and/or dialkyl acid phosphates are represented by theformula (R₁O)(R₂O)P(O)OH, where R₁ is hydrocarbyl and R₂ is hydrocarbylor hydrogen. R₁ and R₂ may have the same or different hydrocarbylgroups.

It is an object of the invention to provide an additive package suitablefor preparing fully formulated lubricating fluids and greases andpreferably having improvements in at least one of the properties ofantiwear protection, oxidative stability, and seal performance.

These and other objects, features, and advantages will become apparentas reference is made to the following detailed description, preferredembodiments, examples, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, like reference numerals are used to denotelike parts throughout the several views.

FIG. 1 is a comparison of TBN for formulations according to embodimentsof the invention versus a commercial additive package.

FIG. 2 is a comparison of the carbon varnish rating of formulationsaccording to embodiments of the present invention versus formulationsoutside of the present invention.

DETAILED DESCRIPTION

According to embodiments of the invention, an additive package isprovided without, or essentially free of, the use of primary, secondary,tertiary, and cyclic hydrocarbyl amine rust inhibitors with carbonnumbers of C30 or less, and/or the corresponding acid phosphate aminesalts which, in certain embodiments, provides improvements in at leastone of the areas of oxidation stability, seal compatibility andanti-wear performance, while causing no appreciable deficits in otherareas of performance. Such lubricant and grease compositions areparticularly useful in automotive gear boxes and differentials as wellas industrial gear boxes.

In preferred embodiments, the additive package of the inventioncomprises an acid phosphate antiwear additive, preferably one or morehydrocarbyl or dihydrocarbyl acid phosphates, said additive packagecharacterized as essentially free of acid phosphate hydrocarbyl aminesalts, where the hydrocarbyl amine is C30 or less, present in said fullyformulated compositions. Until now, it has been believed that thestability of a phosphate-containing antiwear additive was dependent onthe presence of this hydrocarbyl amine such that the phosphorus speciesis present, wholly or at least in part, as a salt of the amine with theacid phosphate. It is the surprising discovery of the present inventorsthat such is not the case. Moreover, improvements in certain importantproperties are evident in certain compositions according to embodimentsof the present invention.

It should be understood that in the expression “effective amount of aacid phosphate antiwear additive”, both the “effective amount” and theidentity of the acid phosphate-containing compound effective as anantiwear additive can readily be determined by one of ordinary skill inthe art in possession of the present disclosure without more thanroutine experimentation.

As used herein, the term “phosphate” does not include any of thesulfur-containing compounds, e.g., thiophosphate compounds. In anembodiment, the acid phosphate may be present as the mono and/ordihydrocarbyl esters of the acid phosphate. The resulting gear lubricantis essentially free of hydrocarbyl primary, secondary, tertiary, andcyclic hydrocarbyl amines with less than or equal to 30 carbons as aningredient (when the invention is expressed as a “recipe” ofingredients) and therefore the final fully formulated lubricant isessentially free of the corresponding acid phosphate amine salts.

In order to avoid misunderstanding, “essentially free of” allows minoramounts, such as inevitable impurities which might lead to the presenceof one or more of primary, secondary, tertiary, cyclic aliphatic amineswith thirty carbons or less (C30 or less) and/or the presence of thecorresponding acid phosphate amine salts, but these ingredients and theconstituents that form them are not present in amounts that effect thenovel and basic characteristics of the present invention.

By omitting these amines from the additive concentrate and ultimatelythe lubricant, the additive system will have a significantly reducedtotal base number (TBN) for the package. The additive concentratescovered by embodiments of this invention have a TBN<22, some cases lessthan 20, or less than 15, or less than 10, or even less than 5.

FIG. 1 is a plot of TBN and TAN (Total Acid Number) of a commercialadditive package versus additive packages which are embodiments of thepresent invention. The commercial additive package was chosen because ithas the lowest TBN in the population of commercial additive packagesexamined by the inventors. All other commercial packages tested by theinventors had higher TBN numbers. It is highly surprising that theadditive packages according to embodiments of the present invention canprovide the benefits set forth herein with low TBN in view of the TBN oftested commercial products.

In addition, by omitting essentially all of the low molecular (≦C30)hydrocarbyl amine rust inhibitors from the gear lubricant, and thereforeeliminating the corresponding phosphate amine salts, a number of veryimportant performance benefits may be achieved in embodiments, which inpreferred embodiments contribute enhanced durability.

The first of these performance benefits is enhanced antiwearperformance. As discussed in the experimental section below, testingaccording to the industry-recognized L-37 rig test (ASTM D6121) hasshown significant improvements particularly in the low temperatureversion (conventionally known as the “Canadian version”) of this test.

Also, in embodiments, the oxidative stability of gear oils without thehydrocarbyl amine rust inhibitor described earlier is superior to thosewith such an amine present. It has been shown by embodiments that whenthese low molecular weight (<C30) hydrocarbyl amines are eliminated froma gear lubricant, the oxidation performance is dramatically improved.This can be demonstrated using the industry oxidation test called theL-60-1 (ASTM D5704).

Improved seal performance was also noted from a gear lubricantformulated in accordance with embodiments of the invention. The ASTMD5562 static seal test was run using both fluoroelastomer (Viton) andpolyacrylate seal materials. In both tests, the elongation percent losswas significantly reduced.

Prior to the present invention, it was expected that fluids formulatedwithout low molecular weight hydrocarbyl amine rust inhibitors would bedeficient in the area of rust inhibition. In embodiments of theinvention, the rust performance of gear lubricants prepared within thescope of the invention was evaluated using the automotive gearindustry's L-33 test (ASTM D7038). The results demonstrate that fluidsformulated in this manner had no steel corrosion deficiencies.

It is preferred that the additive package according to embodiments ofthe present invention also include at least one of the ingredientsselected from the group consisting of: a sulfur-containing extremepressure (EP) agent, a nitrogen-containing dispersant, and a corrosioninhibitor. Other preferred additives may include at least one ingredientselected from the group consisting of: borated dispersants, non-aminicrust inhibitors, defoamants, pour point depressants, antioxidants,demulsifiers, friction modifiers, seal swell agents, chromophores,deodorants, limited slip additives, detergents, and tackifiers.

In an embodiment, the invention is directed to an additive packagecomprising a minor amount of at least one substituted phosphoric acidcomposition characterized by the formula (R₁O)(R₂O)P(O)OH, where R₁ is ahydrocarbyl group and R₂ is either hydrogen or a hydrocarbyl group.

The lubricant composition preferably will also contain asulfur-containing extreme pressure agent, as described more fully below.

The lubricant composition preferably also will containnitrogen-containing dispersants and corrosion inhibitors, with theproviso that said species will be essentially free of low molecularweight primary, secondary, tertiary, cyclic aliphatic mono or polyamineswith a carbon number of C30 or less.

In some instances, the additive package of embodiments of the inventionwill be mixed with, added to, dispersed in, or otherwise formulated tomake a useful product with an oil of lubricating viscosity, such as afluid categorized as being in one of the well-known API Group I-V.Lubricating fluids and greases in accordance with embodiments maycomprise a major amount of such an oil of lubricating viscosity and theadditive package as set forth herein. The term “major amount” meanspresent in an amount greater than any other ingredient, based on wt. %.The “oil of lubricating viscosity” will also be described as a “baseoil” herein, and may be a combination of one or more base oils, with theterm “major amount” meaning the sum of the base oils are present in anamount greater than any other ingredient.

The additive package according to embodiments of the invention maycomprise a small amount of an oil of lubricating viscosity to serve as adiluent and the like, present in a minor amount, such as 0-20 wt %, orabout 0.5 to 15 wt %, or about 1 to 10 wt %, or about 2 to 8 wt %, orabout 4 to 6 wt %, in the additive package. Contemplated ranges includeany of the aforementioned lower limits to any of the aforementionedupper limits, e.g., about 0 to 6 wt %. The term “diluent” as used hereinwill imply a small amount, certainly less than a “major amount” for thesum total of diluent.

The products in accordance with embodiments of the present invention maybe used, for instance, with an oil of lubricating viscosity, for a widevariety of automotive and industrial gear applications. Examples of suchapplications include use in hypoid axles and in mechanical steeringdrives in passenger cars and in cross-country vehicles. In addition, theproduct in accordance with embodiments of the present invention may beused in planetary hub reduction axles, mechanical steering and transfergear boxes in utility vehicles such as trucks. It also can be used indifferent types of gear boxes, e.g. synchromesh gear boxes, as well aspower take-off gears, limited slip axles, and Planetary hub reductiongear boxes. It may also be used in functional fluids, e.g., acirculating or process oil, in metal working, and the like.

It will be recognized that in certain instances it may be convenient tohave a lubricant composition which is not completely formulated solelywith the additive package according to embodiments of the invention,i.e., with a minor amount of additives left to be added by the final endconsumer. However, for the purposes of the present specification, in thephrase “additive package suitable for preparing a fully formulatedlubricant composition” the term “additive package” should be interpretedto mean the sum total of additives that are used to formulate the finallubricant or grease or other functional fluid.

Fluids that can meet the criteria of base oil for lubricant andfunctional fluids are varied. They may fall in any of the well-knownAmerican Petroleum Institute (API) categories of Group I through GroupV. The API defines Group I stocks as solvent-refined mineral oils. GroupI stocks contain the most unsaturates and sulfur and have the lowestviscosity indices. Group I defines the bottom tier of performance. GroupII and III stocks are high viscosity index and very high viscosity indexbase stocks, respectively. The Group III oils contain the lowest levelof unsaturates and sulfur relative to Group I and II oils. With regardto certain characteristics, both Group II and Group III oils performbetter than Group I, particularly in the area of oxidative stability andlow temperature performance.

Group IV stocks consist of polyalphaolefins, which can be produced viathe catalytic oligomerization of linear alphaolefins (LAOs), withparticularly preferable LAOs selected from C5-C14 linear alphaolefins,more preferably from 1-hexene to 1-tetradecene, more preferably from1-octene to 1-dodecene, and mixtures thereof, although oligomers oflower olefins such as ethylene and propylene, oligomers ofethylene/butene-1 and isobutylene/butene-1, oligomers of ethylene withother higher olefins, such as described in U.S. Pat. No. 4,956,122, andthe patents referred to therein, and the like, may also be used. PAOstypically offer superior volatility performance, thermal stability, andpour point characteristics to those base oils in Group I, II, and III.

Group V includes all the other base stocks not included in Groups Ithrough IV. Group V base stocks include, e.g., esters, alkylatedaromatics, polyinternal olefins (PIOs), polyisobutylenes, polyalkyleneglycols (PAGs), etc.

The additive packages as disclosed herein may be formulated with any ofthe above five categories, API Groups I to V, as well as othermaterials.

In preferred embodiments, the additive package includes at least oneingredient selected from the group consisting of: one or moresulfur-containing extreme pressure agents, one or more acid phosphates(pentavalent phosphorus), one or more ashless dispersants, one or morecorrosion inhibitors, and optionally anti-foamants, pour pointdepressants, friction modifiers, demulsifiers, tackifiers, VI improvers,deodorants, seal swell agents, and non-amine rust inhibitors, andmixtures thereof, with the proviso that said lubricating compositionsare essentially free of or completely free of: (a) low molecular weight(≦C30) primary, secondary, tertiary, and cyclic hydrocarbyl amines; and(b) the corresponding acid phosphate amine salts.

While each of the aforementioned ingredients are per se known in theart, preferred ingredients are discussed in more detail below.

Extreme Pressure Agents

Extreme pressure (EP) agents used in the composition according toembodiments of the invention include known sulfur-containing andboron-containing EP agents. Sulfur-containing EP agents are preferred.

Sulfurized olefins are useful in providing protection against highpressure, metal to metal contacts in industrial and automotive gearoils. There is no particular restriction on the sulfur-containingextreme pressure additive that can be used in the additive packageaccording to embodiments of the invention. Sulfur-containing componentsuseful in this regard included sulfurized olefins, dialkyl polysulfides,diarylpolysulfides, sulfurized fats and oils, sulfurized fatty acidesters, trithiones, sulfurized oligomers of C2-C8 monoolefins,thiophosphoric acid compounds, sulfurized terpenes, thiocarbamatecompounds, thiocarbonate compounds, sulfoxides, and thiol sulfinates.Mixtures of sulfur-containing EP components may be used.

The preferred sulfur-containing EP components are selected fromsulfurized oligomers of C2-C8 monoolefins, olefins sulfides, and dialkyland diaryl polysulfides. The more preferred extreme pressure agents areoligomeric olefin sulfides and dialkyl polysulfides. In the mostpreferred embodiment, the sulfurized olefin is prepared via a highpressure sulfurization procedure.

For some gear oil applications, it is possible that boron-containing EPadditives may be adequate, provided that significant amounts of waterare not present to cause hydrolysis. Use of boron-containing EP agentsalone or with sulfur-containing EP agents is a contemplated aspect ofembodiments of the invention. However, in preferred embodiments of theinvention, the composition does not use an extreme pressure ingredientcontaining boron.

Dispersants

Dispersants serve inter alia to keep sludge and varnish particles fromcoating on the gear surfaces. There are no particular restrictions onthe type used, though it is preferable that at least one containsnitrogen. Nitrogen-containing dispersants include alkyl succinimides,alkenyl succinimides, benzylamine compounds (Mannich bases)polybutenylamines, and the like. Borated versions of any of these areoptional.

In preferred embodiments, nitrogen-containing dispersants are selectedfrom alkyl succinimides and alkenyl succinimides. The preferred ashlessdispersant for use in this invention are the products of reaction of apolyethylene polyamine, e.g. tetraethylene pentamine, with ahydrocarbon-substituted anhydride made by the reaction of a polyolefin,preferably having a molecular weight of about 700-5000 and especially800-3000 (it is not particularly important whether this is numberaverage molecular weight or weight average molecular weight) with anunsaturated polycarboxylic acid or anhydride, e.g. maleic anhydride.

Borated dispersants are optional and may be formed by borating ashlessdispersants using suitable boron-containing compounds: boron acids,boron oxides, boron esters, and amine or ammonium salts of boron acids.

Corrosion Inhibitors/Metal Passivators

Corrosion inhibitors or metal passivators are typically additives thatare heterocyclic in nature and are nitrogen-, and optionally,sulfur-containing Triazole and its derivatives have been found toprevent corrosion in gear oils. Some specific examples includebenzotriazole, tolyltriazole, 2-mercaptotriazole, dodecyltriazole. Alkyland aryl derivatives are preferred.

A specific class of passivators is known as “copper passivators.” Thesecomprise a class of compounds which includes thiadiazoles, triazoles,and thiazoles. The preferred compounds are the 1,3,4-thiadiazoles.

Phosphate Anti-Wear Agents

In a preferred embodiment, the additive package includes an effectiveamount of at least one mono- and/or dialkyl acid phosphate for antiwearprotection. An “effective amount” can be determined by one of ordinaryskill in the art in possession of the present disclosure. Preferredmono- and/or dialkyl acid phosphates antiwear additives include at leastone species represented by the formula (R₁O)(R₂O)P(O)OH, where R₁ ishydrocarbyl and R₂ is hydrocarbyl or hydrogen. R₁ and R₂ may have thesame or different hydrocarbyl groups. Suitable hydrocarbyl groups arealkyl groups of 1-40 carbon atoms, preferably 2-20 and more preferably3-20. The preferred acid phosphates for use in this invention areselected from mono- and di-2-ethylhexyl acid phosphates and mixturesthereof.

In prior art compositions, acid phosphates would be present as preformedsalts using a low molecular weight hydrocarbyl amine or the salt wouldbe formed in situ in the additive package and/or the fully formulatedlubricant or grease (or at some other point between prior to or evenduring actual use). Such salts are described in, e.g., U.S. Pat. Nos.2,063,629, 2,224,695, 2,447,288, 2,616,905, 3,728,260, 3,984,448, and4,431,552. The hydrocarbyl amine is often termed a “rust inhibitor” andis usually a low molecular weight (<30 carbons) primary or secondaryamine, but could also be tertiary or cyclic. The preferred amines aregenerally aliphatic in nature and possess from 4-30 carbon atoms. Somespecific examples include the following: octylamine, decenylamine,dodecenylamine, oleylamine, and the like. In some cases, the artdescribes the most preferred amines as a complex with acid phosphates,where the aliphatic group of the amine is a tertiary alkyl group and theamine is a primary amine. Primene 81-R and Primene JMT amines aretypically describes as most preferred.

The present inventors have surprisingly found that by eliminatingessentially all of the low molecular weight hydrocarbyl amine “rustinhibitor”, and (without wishing to be bound by theory) thecorresponding acid phosphate salt complex, the additive system willstill possess adequate rust performance, even without the addition ofother rust inhibitors and will also have, in at least some embodiments,at least one improved property selected from oxidation stability, sealcompatibility and antiwear protection.

Other additives that may be included in the additive concentrateinclude: defoamants, non-aminic rust inhibitors, seal swell agents,friction modifiers, antioxidants, deodorants, chromophores, pour pointdepressants, tackifiers, demulsifiers, detergents, VI modifiers, andmixtures thereof. One of ordinary skill in the art, in possession of thepresent disclosure, can determine the nature and quantity of additivesto provide in the fully formulated lubricant or grease without undueexperimentation.

It should be noted that various ingredients may combine with the otheringredients to form salts, adducts, coordinated species, and the like.The combination of such species may be formed prior to addition to thefinal lubricant fluid, e.g., in the additive package of embodiments ofthe invention, such as in situ with a small amount of diluent (typicallythe final basestock) or they may be formed in situ after the ingredientsare added to the basestock. Various combinations are possible. With thisin mind, the present disclosure thus should be read in the nature of arecipe as regards the various additives described herein.

Furthermore, although all ingredients added to the final fullyformulated lubricating fluid or greases described herein may be providedin a single additive package, the term “additive package” should betaken to mean any one additive package used or the entire sum ofingredients added to the one or more base oils used to create the finalfully formulated composition.

Examples

The following examples are meant to illustrate embodiments of thepresent invention and provide a comparison with lubricant formulationswhich, although heretofore considered adequate for commercial purposes,are not prepared in accordance with the present invention. While theexamples of the invention are described with particularity, they shouldnot be taken to limit the claims. Rather, numerous variations ormodifications will become apparent to (and can be readily made by) thoseof ordinary skill in the art in light of these examples, particularlywhen viewed together with the entire disclosure.

For automotive applications, the oils were tested in the rig tests thatare incorporated into API and SAE standards GL-5 and J2360,respectively. The L-37 test was used to assess antiwear performance; theL-60-1 was used for oxidative and thermal stability; and the static sealtest ASTM D5662 was run for nitrile, polyacrylate and fluoroelastomerseal compatibility. The L-42 for protection against scoring and the L-33and ASTM D130 for corrosion protection were also run to demonstrate nodeficiencies as a result of amine elimination. For industrial gear oils,the ASTM D2783 Four Ball EP test and ASTM D665 for rust were run.

Automotive Example

To evaluate a gear lubricant according to embodiments of the presentinvention, the axle test ASTM D6121 was employed. This particular testis more commonly known as the L-37 test and is used in the industry toevaluate the antiwear performance of an automotive gear lubricant. Thistest method measures a lubricant's ability to protect final drive axlesfrom abrasive wear, adhesive wear, plastic deformation, and surfacefatigue, when subjected to low-speed high-torque conditions. Lack ofprotection can lead to premature gear or bearing failure or both.

The test apparatus is a new, complete, hypoid truck axle assembly, DanaModel 60 with 5.86 to 1 ratio. The assembly is mounted on a test standwith the pinion and axle shafts' center lines horizontal. The gears arefirst run through a conditioning phase and then through a test phase.The test phase is 24 h+0.2 h and is run at 275° F. with a load of 1740ft-lb on each wheel and 80 rpms/min. At the end of the test, thedifferential is disassembled and the ring gear and pinion are inspectedand rated for each type of distress (e.g. spalling, pitting, ridging,wear, rippling, etc.). The rating value is reported.

This same test method is also used for the Canadian version of the test,known as the Low Temperature (LT) L-37. The LT L-37 axle test isrequired for 75W gear oils. This procedure is identical to the regulartemperature L-37, except that the temperature of the test is runapproximately 55° F. lower during both the conditioning and gear testphase.

The oxidative and thermal stability were evaluated in ASTM D5704 or theL-60/L-60-1 test, which is the most common test procedure for evaluatingthese features of automotive gear oils. The test covers theoil-thickening and insoluble/deposit formation characteristics of thelubricant when subjected to high temperature oxidizing conditions. Forthe L-60 test, the candidate lubricant is heated to 325° F./163° C. for50 hr in a small gear box with two lightly loaded spur gears. Air isbubbled through the oil at a rate of 1 L/hr. The viscosity of theoxidized oil is measured at the end of the test and compared to theinitial value. The pentane and toluene insolubles are also measured. TheL-60-1 test is run in the same manner; however, the carbon-varnish andsludge are measured along with the insolubles and viscosity increase.

For seal compatibility, ASTM D5662 was run. This is a laboratory testmethod which evaluates gear oils for compatibility with variouselastomers: nitrile, polyacrylate, and fluoroelastomer. This methodaddresses failures that may be caused by excessive elastomer hardening,elongation loss, and volume swell and attempts to determine thelikelihood that an oil might cause premature sealing system failures inthe field. Specimens are cut from the elastomer being evaluated and areimmersed in oil for 240 hr. Reference oils are run periodically. Thetest temperature is dependent on the type of seal material used: 100° C.for nitrile and 150° C. for fluoroelastomer and polyacrylate. At the endof 240 hr, the aged elastomer specimens are tested for changes inhardness, elongation, tensile strength and volume.

Lubricating compositions, Oils A1 and A2 were prepared in accordancewith the invention, whereas Oils X1 and X2 were formulated forcomparison. The contents of these fluids are shown in Table 1 below. Theadditive systems of all examples use identical components, differingonly in percentages. The additive percentages of X1 and X2 weremanipulated to provide the closest approach to the percent of S, P, andN additives in A1 and A2, respectively, which is believed to provide themost valid comparison. The key difference between A1 and X1, and betweenA2 and X2, is the omission of the hydrocarbyl primary amine rustinhibitor in examples according to embodiments of the present invention.The TBNs for the resulting additive concentrates were calculated using apotentiometric method ASTM D2896. Oils A1 and A2 have a TBN=14.8 andOils X1 and X2 have a TBN=27.9.

TABLE 1 Embodiment of Comparison Embodiment of Comparison Test theInvention Example the Invention Example Oil Code A1 X1 A2 X2 Additivesin Finished Fluid, wt % EP Agent, Mobilad C-175 3.65 4.24 3.65 4.24Antiwear - Mobilad C-421 - Acid Phosphate 1.13 1.37 1.13 1.37 Amine RustInhibitor - Primary Amine (<C30) 0 0.59 0 0.59 Dispersant, Borated andnon-borated 3.51 2.00 3.51 2.00 Copper Passivator - thiadiazole 0.540.25 0.54 0.25 Other additives (inhibitors, antioxidants, 1.19 1.19 1.191.19 defoamants) TBN of Additive System ASTM D2896 14.8 27.9 14.8 27.9 Sin Finished Oil 2.07 2.19 1.95 2.190 P in Finished Oil 0.128 0.157 0.1250.158 N in Finished Oil 0.14 0.14 0.14 0.11 Basestocks, wt % PAO 2, 6cSt 20.0 20.4 26.0 26.4 PAO 150 55.0 55.0 44.0 44.0 Isononyl Heptanoate15.0 15.0 20.0 20.0 Viscometrics of Finished Fluid KV 100° C., cSt ASTMD445 19.65 18.04 11.8 11.3 VI ASTM D2270 216 219 226 229 Brookfield at−40° C., cP ASTM D2983 21,495 17,300 7,318 6,470

In the L-60-1 test, Oils A1 and A2 had much improved carbon varnishratings compared with Oil X1 and Oil X2. The results are shown in Table2. Based on this test alone, the rating results for Oils X1 and X2 areconsidered as “failing”. FIG. 2 shows graphically the superior C-Vperformance of the candidate oils. Since the cleanliness is related tothe C-V rating, it can be clearly stated that the oils A1 and A2 arecleaner. Also, pentane and toluene insolubles were non-existent for OilsA1 and A2 but around 0.3-0.4 mass percent for the oils X1 and X2. Thesludge rating for all four oils was not significantly different.

An improvement in the seal compatibility was also observed for Oils A1and A2 relative to Oil X2 in the seal test ASTM D5662 (testing of X1 wasconsidered superfluous on the basis of the results for X2). The changein percent elongation was reduced for both the fluoroelastomer andpolyacrylate with Oils A1 and A2 (see Table 2 for data), which impliesthat the candidate oils are having less affect on the elastomer than thecomparative Oil X2.

The oils were evaluated in the ASTM D130 Copper Corrosion Test as wellas in the L-33 Rust Test. The copper strip was rated 1b for all fouroils. It is somewhat surprising that formulations without the prior artaminic rust inhibitor achieves the same result as the commerciallyacceptable formulations with the rust inhibitor. In the L-33 test, allformulations were well above the pass/fail line of 9.0 as referenced inSAE J2360 (see Table 2 for data).

The L-42 test is used for determining the anti-scoring properties ofgear lubricants under high speed and shock conditions. It is describedas having the same effect on gears as the start of a drag race. The testunit consists of Dana rear axle 44-1 with a gear ratio of 45:11. In asimilar fashion as the L-37 test, the gears are mounted on a test standwith the pinion and axle shafts' center lines horizontal. The gears areput through a series of accelerations and decelerations againstdynamometers under specified conditions of speed and torque for fourcycles. The gear teeth are inspected at the end of the test for theamount of scoring on the tooth surface. The amount of scoring must beless than or equal to the pass reference oil. Both oils were tested andthe data are presented in Table 2. Oils A1 and A2 had acceptableperformance, proving the absence of the low molecular weight hydrocarbylamine does not hurt scoring performance.

These data reveal that the automotive gear oils A1 and A2 had excellentperformance, despite missing the rust inhibitor. Performance was betterin areas of oxidation, anti-wear and seal performance and in areas thatone might expect to be problematic, e.g. rust and copper corrosion, wasnot affected significantly.

TABLE 2 Embodiment of Comparison Embodiment of Comparison Test theInvention Example the Invention Example Oil Code A1 X1 A2 X2 CopperCorrosion ASTM D130 1b 1b 1b 1b L-37 Test, Uncoated Gears ASTM D6121Pinion Ring Pinion Ring Pinion Ring Pinion Ring Burnish 5 5 5 5 5 5 5 5Discoloration 6 6 6 6 6 7 6 7 Corrosion 10 10 10 10 10 10 10 10 Deposits10 9 10 10 10 10 9 9 Wear 6 8 6 7 7 7 6 7 Scoring 10 10 10 10 10 10 1010 Rippling 8 9 8 9 9 9 8 9 Ridging 8 9 8 9 9 10 8 9 Spitting 9.9 9.99.9 9.9 9.9 9.9 9.9 9.9 Overall Merit 8.94 8.92 9.41 8.92 EvaluationPass Pass Pass Pass L-37 Test, Uncoated Gears, Low Temp. ASTM D6121Pinion Ring Pinion Ring Pinion Ring Pinion Ring Burnish 5 5 5 5 5 5 3 5Discoloration 6 6 6 6 6 7 6 6 Corrosion 10 10 10 10 10 10 10 10 Deposits10 9 10 7 10 9 10 8 Wear 6 8 5 6 6 8 5 6 Scoring 10 10 10 10 10 10 10 10Rippling 9 10 7 9 9 9 6 9 Ridging 9 10 6 6 9 10 6 6 Spitting 9.9 9.9 8.09.9 9.9 9.9 9.0 9.9 Overall Merit 9.56 7.66 9.41 7.66 Evaluation PassFail Pass Fail L-60-1 Test (n = 1) ASTM D5704 % Viscosity Increase 35 2227 18 Pentane Insolubles 0 0.40 0 0.35 Toluene Insolubles 0 0.41 0 0.37Carbon/Varnish 9.7 5.8 9.8 5.0 Sludge 9.5 9.62 9.7 9.49 Evaluation PassFail Pass Fail L-42 % Scoring Ring, Coast 4 3 4 5 % Scoring Pinion,Coast 6 5 9 8 % of Pass/Fail Reference 26 24 33 32 Evaluation Pass PassPass Pass Seal Compatibility ASTM D5662 Fluoroelastomer, % elongationchange −14.7 nd −12.7 −34.9 Polyacrylate, % elongation change 11.0 nd28.0 70.5 Nltrile, % elongation change −55.8 nd −53.4 −56.6 L-33-1 TestASTM D7038 Merit Rating 9.31 9.91 9.56 9.83 Evaluation Pass Pass PassPass

Industrial Gear Fluids

Industrial gear fluids were also formulated in accordance withembodiments of the present invention and one was tested in an effort todemonstrate acceptable performance despite the omitted low molecularweight (≦C30) hydrocarbyl amine and the corresponding phosphate aminesalt. Oil B was one such candidate, i.e. no low molecular weight (≦C30)hydrocarbyl amine was part of the additive system. Here again, theadditive package's TBN was unusually low, measured at 4.5. Table 3 belowshows the composition of the additive system and the mineral base oilsthat were employed.

TABLE 3 Embodiment of Comparison Test the Invention Example Oil Code B YAdditives in Finished Lubricant, wt % EP Agent, Mobilad C-170 0.56 0.56Antiwear - Mobilad C-421 - Acid Phosphate 0.37 0.37 Amine RustInhibitor - Primary Amine (<C30) 0 0.12 Dispersant, Borated andnon-borated 0.09 0.09 Copper passivator - thiadiazole 0.20 0.09 Otheradditives (inhibitors, defoamants, 0.046 0.046 demulsifiers) TBN ofAdditive System ASTM D2896 4.5 27.8 S in Finished Oil (additivecontribution only) 0.275 0.275 P in Finished Oil 0.0440 0.044 N inFinished Oil 0.017 0.015 Basestocks, wt % 150″ Solvent ParaffinicNeutral 12.5 12.5 150 Bright Stock 86.0 86.0 Viscometrics KV, 100° C.ASTM D445 23.6 23.7 KV,  40° C. ASTM D445 306.3 309.3 VI ASTM D2270 9797

To evaluate the performance of the industrial gear lubricant disclosedherein, laboratory bench tests that are part of AIST 224 (formerly USS224), AGMA 9005-E02, and other common industry specifications, wereemployed. Again, antiwear performance and rust protection wereevaluated. ASTM D2783, a Four Ball EP Load Wear Test, measures theantiwear capability of the gear lubricant. One steel ball under load isrotated against three stationary balls immersed in oil. The load isincreased until the weld point in kilograms is determined. The load wearindex, an index of the ability of the lubricant to minimize wear atapplied loads, is also measure. ASTM D4172 uses the Four Ball TestMachine to assess the wear preventive characteristics of lubricatingfluids. A steel ball is rotated atop of three clamped balls at a rate of1800 rpms for 60 min under a force of 20 kg at 75° C. The average wearscar of the three clamped balls is then determined. ASTM D665 is used tomeasure protection from steel corrosion. A mixture of test oil is mixedwith either distilled water (Part A) or synthetic sea water (Part B) ata temperature of 60° C. with a cylindrical steel rod completelyimmersed. After four hours, the test rod is examined for signs ofrusting. Copper corrosion performance was roughly equivalent for the twooils as determined by ASTM D130. The results for Oil B and comparisonOil Y are shown in Table 4.

TABLE 4 Embodiment of Comparison Test the Invention Example Oil Code B YCopper Corrosion ASTM D130 1a 1b Four Ball Wear ASTM D4172 Wear Scar, mm0.31 0.35 Four Ball Weld ASTM D2783 Load Wear Index, kg 53 63 WeldPoint, kg 250 250 Rust Test ASTM D665 Part A Pass Pass Part B Pass Pass

From these results, one can see there is no significant detrimentaleffect for this industrial gear oil when the hydrocarbyl amine rustinhibitors are omitted from the package. The rust test ASTM D665 isreadily passed with both distilled and salt water. Copper corrosionprotection is also satisfactory for the candidate fluid based on ASTMD130 results. The antiwear performance is roughly equivalent asevidenced by the Four Ball Wear and EP test results.

The invention has been described above with reference to numerousembodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims. Nevertheless, a few particularly preferredembodiments may be pointed out. One particularly preferred embodimentincludes an additive package suitable for preparing a fully formulatedlubricating fluid or grease including an effective amount of an acidphosphate-containing antiwear additive, the improvement comprising theabsence of primary, secondary, tertiary, and cyclic aliphatic amineswith a carbon number of C30 or less and the absence of the correspondingacid phosphate amine salts, with still more preferred embodiments, whichmay be combined as would be recognized by one of ordinary skill in theart in possession of the present disclosure, selected from: (i) whereinsaid additive package has a TBN<22 (or TBN<20, or TBN<15, or TBN<10, orTBN<5); (ii) wherein said acid phosphate is selected from at least onemono and/or dihydrocarbyl ester of an acid phosphate characterized bythe formula (I):

(R₁O)(R₂O)P(O)OH  (1)

where R₁ is a hydrocarbyl group and R₂ is selected from hydrogen or ahydrocarbyl group, which may be still more preferably characterized bythe case where the hydrocarbyl groups of R₁ and R₂ are independentlyselected from straight-chained or branched alkyl groups having from 1 to20 carbon atoms, or from 2 to 20 carbon atoms, or from 3 to 20 carbonatoms, and yet still more preferably wherein at least one of thehydrocarbyl groups R₁ and R₂ are 2-ethylhexyl acid phosphate; (iii)characterized as comprising at least one of the following ingredients:(a) at least one sulfur-containing extreme pressure agent; (b) at leastone nitrogen-containing dispersant; (c) at least one corrosioninhibitor; (iv) further comprising at least one ingredient selected fromthe group consisting of borated dispersants, non-aminic rust inhibitors,defoamants, pour point depressants, antioxidants, demulsifiers, frictionmodifiers, seal swell agents, chromophores, deodorants, limited slipadditives, detergents, VI modifiers, and tackifiers. Anotherparticularly preferred embodiment includes an additive package suitablefor use in driveline fluids and/or gear boxes for industrialapplications characterized as essentially free of primary, secondary,tertiary and cyclic hydrocarbyl amines with a carbon number of C30 orless and essentially free of the corresponding acid phosphate aminesalts, more preferably yet wherein said additive package furthercomprising an acid phosphate selected from at least one mono and/ordihydrocarbyl ester of an acid phosphate characterized by the formula(I):

(R₁O)(R₂O)P(O)OH  (1)

where R₁ is a hydrocarbyl group and R₂ is selected from hydrogen or ahydrocarbyl group, and still more preferably at least one of the caseswherein: (i) at least one of the hydrocarbyl groups R₁ and R₂ are2-ethylhexyl; (ii) wherein the composition is further characterized ascomprising at least one of the following ingredients: (a) at least onesulfur-containing extreme pressure agent; (b) at least onenitrogen-containing dispersant; (c) at least one corrosion inhibitor.

Unless specified otherwise herein, the meanings of terms used hereinshall take their ordinary meaning in the art; reference shall be taken,in particular, to Synthetic Lubricants and High-Performance FunctionalFluids, Second Edition, Edited by Leslie R. Rudnick and Ronald L.Shubkin, Marcel Dekker (1999). This reference, as well as all patentsand patent applications, test procedures (such as ASTM methods and thelike), and other documents cited herein are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted. Note that Trade Names used herein are indicated by a ™ symbolor ® symbol, indicating that the names may be protected by certaintrademark rights, e.g., they may be registered trademarks in variousjurisdictions. Note also that when numerical lower limits and numericalupper limits are listed herein, ranges from any lower limit to any upperlimit are contemplated.

1.-21. (canceled)
 22. A method of lubricating an automotive orindustrial gear or differential comprising supplying to said gear ordifferential an additive package for a fully formulated lubricatingfluid and including in said additive package an effective amount of anacid phosphate-containing antiwear additive, wherein the additivepackage is substantially free of primary, secondary, tertiary, andcyclic aliphatic amines with a carbon number of C30 or less and of thecorresponding acid phosphate amine salts.
 23. The method of claim 22,wherein said acid phosphate is selected from at least one mono and/ordihydrocarbyl ester of an acid phosphate characterized by the formula(I):(R₁O)(R₂O)P(O)OH  (1) where R₁ is a hydrocarbyl group and R₂ is selectedfrom hydrogen or a hydrocarbyl group.
 24. The method of claim 22,wherein said additive package has a TBN<22.
 25. The method of claim 22,wherein said additive package has a TBN<20.
 26. The method of claim 22,wherein said additive package has a TBN<15.
 27. The method of claim 22,wherein said additive package has a TBN<10.
 28. The method of claim 22,wherein said additive package has a TBN<5.
 29. The method of claim 22,wherein the hydrocarbyl groups of R₁ and R₂ are independently selectedfrom straight-chained or branched alkyl groups having from 1 to 20carbon atoms.
 30. The method of claim 22, wherein the hydrocarbyl groupsof R₁ and R₂ are independently selected from straight-chained orbranched alkyl groups having from 2 to 20 carbon atoms.
 31. The methodof claim 22, wherein the hydrocarbyl groups of R₁ and R₂ areindependently selected from straight-chained or branched alkyl groupshaving from 3 to 20 carbon atoms.
 32. The method of claim 22, wherein atleast one of R₁ and R₂ is 2-ethylhexyl.
 33. The method of claim 22,wherein said additive package further comprises at least one of thefollowing ingredients: a. at least one sulfur-containing extremepressure agent; b. at least one nitrogen-containing dispersant; c. atleast one corrosion inhibitor.
 34. The method of claim 33, wherein saidadditive package comprises at least two of the ingredients (a)-(c). 35.The method of claim 33, wherein said additive package comprisesingredients (a)-(c).
 36. The method of claim 33, wherein said additivepackage further comprises at least one ingredient selected from thegroup consisting of borated dispersants, non-aminic rust inhibitors,defoamants, pour point depressants, antioxidants, demulsifiers, frictionmodifiers, seal swell agents, chromophores, deodorants, limited slipadditives, detergents, VI modifiers, and tackifiers.
 37. The method ofclaim 22, wherein the gear is incorporated in a device selected from thegroup consisting of planetary hub reduction axles, mechanical steeringand transfer gear boxes in utility vehicles, synchromesh gear boxes,power take-off gears, limited slip axles, and planetary hub reductiongear boxes.